This invention relates to telecommunications terminals. Particularly the invention involves an access terminal.
Telecommunications terminals connect subscriber lines, such as POTS (Plain Old Telephone Service) and ISDN (Integrated Services Digital Network) lines, to telecommunications equipment such as a telecommunications switch, e.g., a class 5 switch. Telecommunications switches connect and route messages between different lines.
A telecommunications terminal contains channel unit card slots that accept channel unit cards. Channel unit cards convert analog and digital signals from subscriber lines into formatted digital data signals. Different types of channel unit cards service different types of subscriber lines (e.g. POTS or ISDN). The terminal constructs one or more time division multiplexed (TDM) signals from several channel unit cards"" formatted digital data signals for transmission to remote telecommunications equipment for example, another telecommunications terminal. The terminal also demultiplexes TDM signals received from remote telecommunications equipment to deliver formatted digital data back to the channel unit cards. Channel unit cards convert the formatted digital data into a form suitable for transmission over subscriber lines.
Two telecommunications terminals can be connected xe2x80x9cback-to-backxe2x80x9d to form a digital loop carrier (DLC) network. A DLC typically includes a remote terminal (RT) placed near a business or residence and a central terminal (CT) placed in a central exchange connected to a telecommunications switch. The RT and CT communicate over a single or multiple lines carrying TDM signals. This configuration connects subscribers to the telecommunications switch via the DLC network.
A digital loop carrier (DLC) at a central terminal (CT) includes a multiplexor which, using TDM, can multiplex multiple analog and digital signals from subscriber telephone lines into a single or multiple T1 signal. A mirror DLC located at a remote terminal (RT) can decode the multiplexed T1 signal into a form suitable for transmission over subscriber telephone lines. This data flow also occurs in the opposite direction from RT to CT.
A method of switching subscriber calls includes receiving a subscriber call on an access terminal, determining whether the access terminal is in communication with a telecommunications network and routing the subscriber call through alternate telecommunications equipment if the access terminal is not in communication with the telecommunications network.
The method may also include determining whether the subscriber call request is to another subscriber connected to the access terminal and switching the subscriber call request within the access terminal to another subscriber connected to the access terminal. The routing may include switching the subscriber call through alternate telecommunications equipment to another access terminal which may also not be in communication with the telecommunications network during the routing of the subscriber call. The method may include routing the subscriber call from another access terminal to the telecommunications network.
The access terminal may be a remote terminal and the other access terminal may be a central office terminal. If the access terminal is not in communication with the controller, the access terminal indicates that service is not available to subscriber call requests not to other subscribers connected to the access terminal, if the access terminal is not in communication with the controller.
Also, the method may include recording subscriber calls and call attempts while the access terminal is not in communication with the telecommunications network. At least some central office functionality may be provided while the access terminal is not in communication with the telecommunications network, possibly by a resource card with a digital signal processor.
A telecommunications network has a digital loop carrier including access terminals coupled to a switching network. A controller connected to the access terminals is included. Also, a processor is provided in at least one of the access terminals for routing subscriber call requests to other subscribers on the same access terminal, routing subscriber call through the switching network when the communication link between the access terminal and the switching network is functioning and routing subscriber calls to alternate telecommunications equipment when the communication link between the access terminal and the switching network is malfunctioning.
The processor may indicate that service is not available to subscriber call requests not to other subscribers connected to the access terminal when the communication link between the access terminal and the controller or switching network is malfunctioning, record subscriber calls and call attempts while the communication link between the access terminal and the controller or switching network is malfunctioning and provide at least some central office functionality while the communication link between the access terminal and the switching network is malfunctioning.
Software, residing on a computer-readable medium, for an access terminal in a telecommunications network including access terminals coupled to a switching network and a controller connected to the access terminals is provided. The software includes instructions to cause one or more processors to route subscriber calls within the access terminal to other subscribers connected to the access terminal, determine whether a communications link between the access terminal and the switching network is malfunctioning and route subscriber calls to alternative telecommunications equipment when the communications link between the access terminal and the switching network is determined to be malfunctioning.
The software may include instructions to determine whether a communications link between the access terminal and the controller or switching network is malfunctioning and indicate that service is not available to subscriber call requests not to other subscribers connected to the access terminal when the communication link between the access terminal and the controller or switching network is determined to be malfunctioning.
The software may include instructions to record subscriber calls and call attempts while the communication link between the access terminal and the switching network is malfunctioning and instructions to provide at least some central office functionality while the communication link between the access terminal and the controller or switching network is malfunctioning.
Advantages may include one or more of the following. Switching of local calls is handled by a remote terminal receiving the calls. As a result, local subscriber calls always will be completed even if a remote terminal is isolated from its network. Also, if a remote terminal is severed from its central office terminal, calls can be completed by routing them through alternative telecommunication equipment. Other advantages will become apparent from the following description including the drawings and claims.